(1) Field of the Invention
The present invention concerns the field of digital signal receivers provided with means of synchronisation with the transmitter and more particularly digital synchronisation means.
(2) Description of Related Art
The context is the transmission of a bit stream consisting of a series of bits that can take the value 0 or 1. This bit stream is generated by the transmitter at a period defined by its internal clock.
The receiver, in order to succeed in receiving the transmitted signal, must be in a position to sample the bits sent while complying with the period of the transmitter. The receiver has its own internal clock. It is necessary to synchronise these clocks in order to compensate for any drift due to limited precision of the components.
This synchronisation may be done by means of a common external reference, typically the reception of a clock signal transmitted by the global positioning system (GPS).
Using an analogue solution is also known. From information injected into the signal by the transmitter, a local precision oscillator is adjusted continuously in order to align its frequency on the frequency of the transmitter. This is done by means of components of PLL (Phase Locked Loop) or VCO (Voltage Controlled Oscillator) type.
These solutions require components with a cost that is high for simple embodiments.